Moisture vapor permeable materials

Abstract

Polymeric materials are provided characterized by hard segments and copolymer soft blocks comprising hydrophobic and hydrophilic components. The polymeric materials may be mixed with a base polymer and/or inorganic salts. The polymeric materials and mixtures containing same are characterized by improved moisture vapor transmission rates. The polymeric materials may be formed into films for use as wound dressings, burn dressings, surgical drapes, semipermeable membranes, and coatings for textiles.

What is claimed is: 
     
       1. A nonporous segmented block multipolymer film impermeable to liquid water and characterized by a high moisture vapor transmission rate comprising an essentially linear segmented copolymer chain characterized by a) at least one hard segment, and   b) at least two soft segments, a1) said hard segment being selected from the group consisting of reaction products of organic diisocyanates with a11) a diamine, and   a12) a diol,     b1) said soft segments comprising b11) at least one hydrophilic soft segment, and   b211) said hydrophilic soft segment, b111) said hydrophilic soft segment consisting of ethylene oxide and up to at most 20% by weight of propylene oxide,   b211) said hydrophobic soft segment consisting of polytetramethylene oxide,      whereby the hydrophilic and the hydrophobic soft segments are separated from each other by hard segments.       
     
     
       2. A film according to claim 1, wherein said organic diisocyanate is selected from the group consisting of diphenylmethane diisocyanate and dicyclohexyl diisocyanate. 
     
     
       3. A film according to claim 1, which further comprises up to 2% by weight of a polydialkylsiloxane segment. 
     
     
       4. A film according to claim 1, comprising:   ______________________________________                                    
15-50%    by weight of said hard segment                                  
20-45%    polyethylene oxide                                              
          with a number average mol weight of between                     
          1000-3000                                                       
25-65%    polytetramethylene oxide                                        
100%                                                                      
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       5. A film according to claim 3, wherein the polydialkylsiloxane is polydimethylsiloxane.